Types of Galactosemia

Classic galactosemia (type I) is the most severe form. If infants with classic galactosemia are not treated quickly with a galactose-free diet, life-threatening complications occur shortly after birth.

Both parents must pass on a defective copy of the GALT gene for their child to develop classic galactosemia. The newborn screening test in all 50 states screen for this type of galactosemia.

Variant Duarte Galactosemia

Like classic galactosemia, duarte galactosemia is caused by a mutation in the GALT gene, but it is much less severe. Children with duarte galactosemia typically do not have serious symptoms and may or may not require a restricted diet.

Galactokinase deficiency galactosemia is due to a mutation in the GALK1 gene, making it impossible for an affected child to fully break down galactose. Not all newborn galactosemia screening tests cover this version of the deficiency, so a normal result can be misleading.

Galactosemia type III results from inheriting mutated GALE genes, which causes a partial loss of activity in the GALE enzyme. Three types of epimerase deficiency exist: generalized, intermediate, and peripheral. Generalized epimerase deficiency is like classic galactosemia in terms of severity. As with galactosemia type II, many newborn screening tests do not screen for epimerase deficiency.